普通java类(排序)实现Comparable接口重写CompareTo方法

原文地址为： 普通java类(排序)实现Comparable接口重写CompareTo方法

普通的类要实现排序，必须实现Comparable接口，并重写CompareTo()方法。 

package test;

public class Field implements Comparable<Field> {

private String name;
private int age;

public Field() {
    }
public Field(String name, int age) {
this.name = name;
this.age = age;
    }
public String getName() {
return name;
    }
public void setName(String name) {
this.name = name;
    }
public int getAge() {
return age;
    }
public void setAge(int age) {
this.age = age;
    }

    @Override
public int compareTo(Field o) {
// 先按age排序
if (this.age > o.getAge()) {
return (this.age - o.getAge());
        }
if (this.age < o.getAge()) {
return (this.age - o.getAge());
        }
// 按name排序
if (this.name.compareTo(o.getName()) > 0) {
return 1;
        }
if (this.name.compareTo(o.getName()) < 0) {
return -1;
        }
return 0;
    }
}

 测试类按照某属性进行排序输出：

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Test2 {
public static void main(String[] args) {

        Field f1 = new Field("tony", 11);
        Field f2 = new Field("jack", 11);
        Field f3 = new Field("tom", 11);
        Field f4 = new Field("jason", 44);

        List<Field> list = new ArrayList<Field>();
        list.add(f1);
        list.add(f3);
        list.add(f4);
        list.add(f2);
Collections.sort(list);

for (Field o : list) {
            System.out.println(o.getAge() + "-->" + o.getName());
        }
    }
}

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